This Cooperative Clinical Study was initiated in order to test whether or not adequate radiotherapy can be considered curative in inoperable carcinoma of the prostate which is limited to the pelvis. For this purpose the protocol and forms were developed permitting a rather comparable performance of the various institutions under adequate control. The Physics Center visited and checked every institution for performance and accurate dosimetry. The histopathology of every case has been verified by the Study's pathologist. The follow-up of the cases has been adequate and the data has been accumulating satisfactorily.